Louise Seguin, age 17, of St. Catharines, Ontario, Canada, for her question:

WHAT IS PYROMETRY?

Pyrometry is a system of measuring temperatures and usually refers to temperatures that are too high to be measured by ordinary thermometers.

In pottery kilns, where it is necessary to measure not only the temperature but also the effect of the heat, pyrometric or Seger cones are sometimes used. These small pyramid shaped cones are made of clay and salt and will melt after being at a certain temperature for a given length of time. Unfired rings of clay are also used in kilns to measure the work done by heat.

Pyrometers are used when it is necessary to measure only the high temperature. One kind matches the color in the furnace against known temperatures of red hot wires. Pyrometry is important in heat treating metals and in making glass.